<!--
 * @Description:for循环金字塔.html
 * @Author: Sun
 * @Date: 2019-07-01 20:05:50
 * @LastEditors: Sun
 * @LastEditTime: 2019-07-13 23:38:36
 -->
<!DOCTYPE html>
<html lang="en">

<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<meta http-equiv="X-UA-Compatible" content="ie=edge">
	<title>for循环金字塔</title>
	
	<script>
		window.onload = function () {
      for (let index = 1; index <= 100; index+=3) {
				// const element = array[index];

				 document.write(`<hr width=${index}%/>`);

				
			}
		}
	</script>
</head>

<body>
  <div>

	</div>
</body>

</html>